# Pipe Friction Tables - by Nelsen Corporation

### Friction loss

Pipe friction is the resistance to flow created by the interior surface of the pipe through which a liquid is moving. The smaller the diameter of the pipe, or greater the rate of flow, the greater the amount of friction (friction loss).

Friction loss is expressed as feet of head in 100 feet of pipe and will vary depending upon the material of which the pipe is made. The following charts show friction losses in steel, copper, and plastic pipe, Pipe size should be sufficiently large so that not more than 10% of the total dynamic head is in friction loss.

Equivalent Number of Feet Straight Pipe for Different Fittings
Size of fittings, Inches1/2"3/4"1"1-1/4"1-1/2"2"2-1/2"3"4"5"6"
90° EII1.522.73.54.35.56.58101415
45° EII0.811.31.722.533.856.37.1
Long sweep EII11.41.72.32.73.54.25.27911
Close return bend3.6568.310131518243137
Tee-straight run1223345
Tee-side inlet or outlet3.34.55.77.69121417222731
Globe valve open1722273643556782110140160
Angle valve open8.412151822283342587083
Gate valve - fully open0.40.50.60.811.21.41.72.32.93.5
Check valve (Swing)457911131620263339
Chcek valve (Spring)46812141923324358

Figure friction loss for 118.5 ft. of pipe

(B) Assume flow to be 80 GPM through 2" plastic pipe.
Friction loss table shows 10.9 ft. loss per 100 ft. of pipe.

1. In step (A) we have determined total feet of pipe to be 118.5 ft.
2. Convert 118.5 ft. to percentage 118.5 ÷ 100 = 1.185.
3. Multiply 10.9 x 1.185 = 12.9165 or 12.92 ft. = Total friction loss in this system

Example

(A) 100 ft. of 2" plastic pipe with one (1) 90° elbow and one
(1) swing check valve.

90° elbow — Equivalent to5.5 ft. of straight pipe
Swing Check — Equivalent to13.0 ft. of straight pipe
100 ft. of pipe — Equivalent to100.0 ft. of straight pipe
118.5 ft. = Total equivalent pipe

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Figure friction loss for 118.5 ft. of pipe

(B) Assume flow to be 80 GPM through 2" plastic pipe.

1. Friction loss table shows 10.9 ft. loss per 100 ft. of pipe.
2. In step (A) we have determined total feet of pipe to be 118.5 ft.
3. Convert 118.5 ft. to percentage 118.5 ÷ 100 = 1.185.
4. Multiply 10.9 x 1.185 = 12.9165 or 12.92 ft. = Total friction loss in this system

Example

(A) 100 ft. of 2" plastic pipe with one (1) 90° elbow and one

(1) swing check valve.

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